Abstract

Introduction

Immunological studies of giant cell arteritis (GCA) suggest that a triggering antigen
of unknown nature could generate a specific immune response. We thus decided to detect
autoantibodies directed against endothelial cells (ECs) and vascular smooth muscle
cells (VSMCs) in the serum of GCA patients and to identify their target antigens.

Results

Serum IgG from GCA patients recognised 162 ± 3 (mean ± SD) and 100 ± 17 (mean ± SD)
protein spots from HUVECs and VSMCs, respectively, and that from HCs recognised 79
and 94 protein spots, respectively. In total, 30 spots from HUVECs and 19 from VSMCs
were recognised by at least two-thirds and three-fifths, respectively, of the pools
of sera from GCA patients and not by sera from HCs. Among identified proteins, we
found vinculin, lamin A/C, voltage-dependent anion-selective channel protein 2, annexin
V and other proteins involved in cell energy metabolism and key cellular pathways.
Ingenuity pathway analysis revealed that most identified target antigens interacted
with growth factor receptor-bound protein 2.

Conclusions

IgG antibodies to proteins in the proteome of ECs and VSMCs are present in the sera
of GCA patients and recognise cellular targets that play key roles in cell biology
and maintenance of homeostasis. Their potential pathogenic role remains to be determined.